1. Field of Invention
The present invention relates to a Micro-Electro-Mechanical System (MEMS) chip and a package method thereof.
2. Description of Related Art
In a process for making a MEMS chip, an internal MEMS device, such as a micro-acoustical sensor, gyro-sensor, or accelerometer, is often required to be packaged in a sealed space to maintain its stability. Conventionally, a package process is performed after the MEMS device is “released”, i.e., after the MEMS device becomes a movable structure by an etching step. A device wafer with the MEMS device formed therein is bonded with a capping wafer by a bonding material such as aluminum or glass material. However, when the MEMS device is made by a CMOS compatible process, because the MEMS device is packaged after it is released, and since the MEMS device made by the CMOS compatible process uses aluminum or other material which can not sustain high temperature, the package method suffers many constraints. In addition, the MEMS device made by the CMOS compatible process is also more likely to be damaged during the package process.
The present invention provides a MEMS chip structure and a package method thereof to reduce the impact by the temperature and enhance the yield of the MEMS device.